U.S. patent number 6,423,883 [Application Number 09/353,470] was granted by the patent office on 2002-07-23 for liquid reception medium with liquid activated mechanical mass transport means.
This patent grant is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Bryan David Haynes, Michael Tod Morman, Thomas Harold Roessler.
United States Patent |
6,423,883 |
Morman , et al. |
July 23, 2002 |
Liquid reception medium with liquid activated mechanical mass
transport means
Abstract
A liquid reception device as a component, for example, of a
personal care product such as a disposable diaper, an incontinent
garment, or for other applications such as, for example, an
industrial soaker pad or the like. The device includes liquid
activated means to move a liquid insult from a target zone to a
peripheral zone. The liquid activated transport means operated
mechanically by suction created by compression or vacuum or by
physical movement of a liquid container from the target zone to the
peripheral zone. The disclosed device provides increased use of
available liquid handling capacity.
Inventors: |
Morman; Michael Tod
(Alpharetta, GA), Haynes; Bryan David (Cumming, GA),
Roessler; Thomas Harold (Menasha, WI) |
Assignee: |
Kimberly-Clark Worldwide, Inc.
(Neenah, WI)
|
Family
ID: |
23389259 |
Appl.
No.: |
09/353,470 |
Filed: |
July 13, 1999 |
Current U.S.
Class: |
604/368; 604/313;
604/383; 604/385.101 |
Current CPC
Class: |
A61F
13/47263 (20130101); A61F 13/53708 (20130101); A61F
2013/1539 (20130101); A61F 2013/53782 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61F 013/15 () |
Field of
Search: |
;604/313,317,331,347,327-329,355,378-380,322,356,358,367-369,383,385.01,393
;602/41-46,48-51,58,13 ;428/34.5-34.7,131,133,137,304.4,295.1
;128/760-762,894,769,287,290,284,118.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Weiss; John G.
Assistant Examiner: Webb; Jamisue
Attorney, Agent or Firm: Herrick; William D.
Claims
We claim:
1. A liquid reception device comprising: (a) a liquid receiving
layer having a target zone; (b) a peripheral zone located within or
outside said liquid receiving layer; (c) mechanical transport means
located partially within said target zone and adapted for liquid
communication with said peripheral zone; and comprising: (i) at
least one tube having at least one sealed opening within said
target zone; (ii) suction means comprising a compressed bulb
containing a superabsorbent connected to said at least one tube for
drawing said liquid through said at least one tube from said target
zone to said peripheral zone; and (iii) means for opening said at
least one sealed opening activated by contact with said liquid
thereby causing said suction means to draw said liquid.
2. The liquid reception device of claim 1 comprising a plurality of
layers each containing said one at least tube.
3. The liquid reception device of claim 1 wherein at least one of
said tube has a plurality of said apertures with said liquid
activated opening means.
4. The liquid reception device of claim 3 wherein said plurality of
apertures are adapted to transport a plurality of liquid
insults.
5. The liquid reception device of claim 1 as a component of a
disposable diaper.
6. The liquid reception device of claim 1 as a component of an
incontinent product.
7. The liquid reception device of claim 1 as a component of a
soaker pad.
8. The liquid reception device of claim 1 as a component of a
personal care product.
9. The liquid reception device of claim 1 wherein said sealed
opening comprises a gelatin.
10. A liquid reception device comprising: (a) a liquid receiving
layer having a target zone; (b) a peripheral zone located within or
outside said liquid receiving layer; (c) mechanical transport means
comprising a seal for suction retention located partially within
said target zone and adapted for liquid communication with said
peripheral zone; and (d) means activated by contact with liquid to
cause transport of said liquid from said target zone to said
peripheral zone.
11. A liquid reception device comprising: (a) a liquid receiving
layer having a target zone; (b) a peripheral zone located within or
outside said liquid receiving layer; (c) mechanical transport means
located partially within said target zone and adapted for liquid
communication with said peripheral zone; and (d) means activated by
contact with liquid to cause transport of said liquid from said
target zone to said peripheral zone and comprising:
(i) liquid containment means located in said target zone and
adapted to collect said liquid; (ii) retractive means connecting
said containment means to said peripheral zone; and (iii) liquid
activated means to cause retraction of said retractive means and
move said liquid containment means from said target zone to said
peripheral zone.
12. The liquid reception device of claim 11 wherein said retractive
means comprises an elastic selected from elastomers and
thermoplastic elastomers.
Description
FIELD OF THE INVENTION
The present invention relates to media for reception of liquid such
as absorption, retention, and transfer components of personal care
products like disposable diapers, training pants, swimwear,
incontinent protective devices and feminine care sanitary napkins
and the like. While many improvements have been made to liquid
reception media for these and other uses, some products still tend
to be bulky and, in use, cause the wearer to be self conscious.
Moreover, packaging, shipping and storage of such bulky products
represent significant costs. Finally, disposal of used product has
been indicated by some to represent an opportunity for
environmental improvement. It has been long recognized that a more
efficient medium for receiving, transfer and/or absorption would
permit significant reduction in the amount of absorbent material
needed and favorably impact each of the above issues. The present
invention is directed to such a liquid reception medium.
BACKGROUND
One measure of the efficiency of a liquid absorbent medium is its
ability to move the liquid being absorbed within the medium from
the point of delivery to areas throughout the entire absorbent
medium so that the total available capacity of the medium to absorb
is utilized. Much research effort has been expended developing ways
to accomplish this movement of liquid. For example, special fiber
shapes and spacing have been used to create and enhance the
capillary forces which cause fluids to move in an absorbing medium,
and treatments have been developed that act on liquids being
absorbed and the absorbing media itself. In addition, the
configuration of the medium has been modified such as by creating
embossed channels or folds intended to direct liquid movement.
While these efforts have had a measured degree of success, there
remains a need for even better measures to quickly move relatively
large liquid volumes (insults) from a delivery or target zone to a
peripheral area either within the liquid receiving component or in
another absorbent component. The result will reduce leakage and/or
allow reduced amounts of absorbent material to be used to make more
conforming products and provide environmental benefits.
Capillary movement of liquids either using the capillary structure
between fibers or pore structures within foams, for example, is
relatively slow. Movement of mass quantities of liquid resulting
from gush or surge insults can, of course, be accomplished by
collecting the liquid and displacing it by physical means to
another area of the absorbent product. Practical means for
accomplishing this displacement, however, are not well defined or
developed to date. One effort described in U.S. Pat. No. 5,769,834
to Reiter et al., relies on an apertured tube and pumping action
from decompression and compression by bodily movements of a wearer
of a diaper, as an example. The liquid movement is thus dependent
on the movement of the wearer. U.S. Pat. No. 5,902,297 to Sauer is
directed to an absorbent article with conduit means for collecting
and transporting fecal matter. The present invention relates to
different mechanical structures of absorbent product components to
accomplish the desired result in a reliable and effective
manner.
SUMMARY OF THE INVENTION
The present invention provides a liquid reception device having one
or more component layers and that includes a layer having a target
zone and that includes in the device a peripheral absorption zone
either within or outside the layer having a target zone. A liquid
transport means is included within the target zone and extends to
the peripheral zone. Upon liquid contact the liquid transport means
is activated to move a mass amount of liquid from the target zone
to a peripheral zone. The liquid transport means can be, for
example, a tube which is connected to a suction device and is
sealed by a liquid dissolvable seal. When contacted by liquid, the
seal is dissolved and the end of the tube or other previously
sealed part opened to draw liquid by means of the suction device.
Another means can be a collapsed sealed tube containing a liquid
expandable material such as a superabsorbent or collapsed foam.
When the seal is dissolved, the collapsed tube is forced to expand.
The expansion creates a void volume and thus a vacuum. The liquid
is pulled into the tube by the vacuum. As the liquid contacts the
superabsorbent, the superabsorbent swells, causing the tube to
further expand. Ideally, the tube will readily expand to a larger
dimension than its original, pre-compressed dimension so the
absorption/expansion/vacuum generation cycle will continue. Another
transport means includes a collection device attached by a
dissolvable adhesive in the target zone and also by elastic means
to an area in the peripheral zone. Liquid contact causes the
collection means to be released from the target zone and displaced
to the peripheral zone. The collection device could be a stretched
superabsorbent fiber which is permanently attached in the periphery
of the product and attached in the target area by a slowly
dissolving water soluble adhesive. The filament would absorb
liquid, the adhesive dissolve, and be pulled up into the periphery
of the product. In all cases the structure requires only liquid
contact to activate the mechanical liquid transport means.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial view in cross-section of an absorbent product
incorporating one embodiment of the present invention.
FIG. 2 is an enlarged view of a product like that of FIG. 1 using a
different embodiment of the present invention.
FIG. 3 is a view like that of FIG. 2 showing a further embodiment
of the present invention.
FIG. 4 is a view in cross-section of one liquid movement element in
accordance with the present invention prior to liquid contact.
FIG. 5 is a view of the element of FIG. 4 after liquid contact.
FIG. 6 is a view in cross-section of another liquid movement
element in accordance with the present invention prior to liquid
contact.
FIG. 7 is a view of the element of FIG. 6 after liquid contact.
FIG. 8 is a view in cross-section of another liquid movement
element in accordance with the present invention prior to liquid
contact.
FIG. 9 is a view of the element of FIG. 8 after liquid contact.
FIG. 10 is a view in cross-section of another liquid movement
element in accordance with the present invention prior to liquid
contact.
FIG. 11 is a view of the element of FIG. 10 after liquid
contact.
FIG. 12 is a graph of weight change, over time comparing the
invention with a standard liquid reception material.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
As used herein, the term "tube" means an element having a length
exceeding its width and a central portion along its length that
permits liquid flow and that is surrounded by an outside skin or
portion that contains liquid within the central portion. An obvious
example is a drinking straw, but other examples can include solid
elements with a high liquid transport center containing
superabsorbent fibers.
As used herein, the term "medium" means a structure having
interconnected pores that allow liquid to enter and flow in one or
more directions. Examples include foams and fibrous webs.
As used herein, the term "superabsorbent" means a water-swellable,
water-insoluble organic or inorganic material capable, under the
most favorable conditions, of absorbing at least about 10 times its
weight and, preferably, at least about 20 times, more preferably
about 30 times, its weight in an aqueous solution containing 0.9
weight percent of sodium chloride. Organic materials suitable for
use as a superabsorbent material of the present invention can
include natural materials such as agar, pectin, guar gum, and the
like, as well as synthetic materials such as synthetic hydrogel
polymers. Such hydrogel polymers include, for example, alkali metal
salts of polyacrylic acids, polyacrylamides, polyvinyl alcohol,
ethylene maleic anhydride co-polymers, polyvinyl ethers,
hydroxypropyl cellulose, polyvinyl morpholinone, and polymers and
copolymers of vinyl sulfonic acid, polyacrylates, polyacrylamides,
polyvinyl pyridines, and the like. Other suitable polymers include
hydrolyzed acrylonitrile grafted starch, acrylic acid grafted
starch, and isobutylene maleic anhydride copolymers and mixtures
thereof. The hydrogel polymers are preferably lightly cross-linked
to render the material substantially water insoluble. Cross-linking
may, for example, be by irradiation, or by covalent, ionic, Van der
Waals, or hydrogen bonding. Preferred superabsorbent materials are
shell cross-linked so that the outer surface or shell of the
superabsorbent particle, fiber, flake, sphere, etc. possesses a
higher cross-link density than the inner portion of the
superabsorbent. The superabsorbent materials may be in any form
suitable for use in absorbent composites including particles,
fibers, flakes, spheres, and the like. In one preferred embodiment
of the present invention, the superabsorbent material comprises
particles of hydro-colloids, preferably anionic hydro-colloids.
As used herein, the term "liquid" has its usual meaning and
includes nonparticulate materials capable of flowing and assuming
the shape of an opening or container receiving them. Examples
include aqueous liquids such as urine and blood products for which
personal care products are designed and do not exclude particulate
components that do not prevent the described flow such as may be
found in runny bowel movements ("BM") for example.
As used herein, the term "mechanical" means an operation that
includes movement of a structure or element of a structure.
Examples include 1) expansion or contraction of walls of a space
defining component such as a tube or bulb or 2) stretching or
contraction of an elastic component.
As used herein, the term "target" means an area, zone, or volume
expected to be one of the first to receive a liquid insult for a
particular product application. It will be recognized by those
skilled in the art that the target area size will vary depending on
the particular product applications and wearer. However, in
general, the target area will include that portion of the medium
which the liquid involved would occupy or flow after a three second
period in use. For purposes of this description, the target may be
covered by another layer or component, such as a diaper liner, for
example, and in that context may not be the first liquid contact
point.
As used herein, the term "peripheral" means an area outside of the
target area.
As used herein, the term "mass transport" means movement of the
liquid involved at a rate that is at least effective to maintain
the ability of the target zone to receive a second or additional
insult without exceeding its absorbent capacity as indicated by
excessive leaking.
As used herein, the term "elastic" means an element having a
retractive force from an elongation. Examples include a stretched
rubber band.
As used herein the term "nonwoven fabric or web" means a web having
a structure of individual fibers or threads which are interlaid,
but not in an identifiable manner as in a knitted fabric. Nonwoven
fabrics or webs have been formed from many processes such as for
example, meltblowing processes, spunbonding processes, and bonded
carded web processes. The basis weight of nonwoven fabrics is
usually expressed in ounces of material per square yard (osy) or
grams per square meter (gsm) and the fiber diameters useful are
usually expressed in microns. (Note that to convert from osy to
gsm, multiply osy by 33.91).
As used herein the term "spunbonded fibers" refers to small
diameter fibers which are formed by extruding molten thermoplastic
material as filaments from a plurality of fine, usually circular
capillaries of a spinnerette with the diameter of the extruded
filaments then being rapidly reduced as by, for example, in U.S.
Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to
Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S.
Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No.
3,502,763 to Hartman, U.S. Pat. No. 3,502,538 to Levy, and U.S.
Pat. No. 3,542,615 to Dobo et al. Spunbond fibers are generally not
tacky when they are deposited onto a collecting surface. Spunbond
fibers are generally continuous and have diameters larger than 7
microns, more particularly, between about 10 and 20 microns.
As used herein the term "polymer" generally includes but is not
limited to, homopolymers, copolymers, such as for example, block,
graft, random and alternating copolymers, terpolymers, etc. and
blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configuration of the material. These configurations
include, but are not limited to isotactic, syndiotactic and random
symmetries.
As used herein and in the claims, the term "comprising" is open and
does not exclude additional elements, ingredients, or process steps
which do not prevent operation of the invention.
EXAMPLES
For purposes of exemplifying the present invention, the particular
product application is not critical. The invention will be
described generally as a disposable diaper having basic components
of a liner, absorbent layer, and backing and which may include
additional components such as a surge layer. It will be apparent to
those skilled in the art that the particular product may take
numerous forms and include more or less elements. For example, a
soaker pad may not require a liner, and an incontinent garment may
have a belt, straps, or other ways to maintain its position on the
wearer. These and other applications which can take advantage of
the ability to rapidly mass transport in accordance with the
invention are all contemplated and embraced by the description and
claims which follow.
Turning to the drawings, FIG. 1 illustrates in cross-section a
partial view of a disposable diaper 10 having a liquid permeable
liner 12, absorbent layer 16, surge layers 14 and liquid
impermeable backing 18. In this case the mass transport means is a
tube 20 located between the absorbent layers 16 and the backing 18
and extending from the target area 22 to the peripheral area 24.
The tube 20 is in communication with a collapsed expandable bulb 28
in the peripheral area 24 and sealed by means of a liquid soluble
seal 26 at the opposite end located in the target area 22. Upon
liquid insult In the target area 22, contact between the liquid and
seal 26 causes the seal to fail allowing the bulb 28 to expand
drawing liquid through the tube 20 from the target area 22 to the
peripheral area 24. If additional expansion is desired, the
collapsed bulb may contain a superabsorbent that will expand when
wetted and further expand the bulb drawing additional liquid
through the tube.
FIG. 2 illustrates in schematic cross-section an alternative
mechanism for moving liquid that includes a series of collapsed
expandable tubes 30 next to each other and extending in the target
area 34 to peripheral areas 35. Tubes 30 extend in both directions
from target area 34 to peripheral areas 35, and each has a liquid
soluble seal 36 in the target area 34. On liquid contact, the seal
36 dissolves allowing liquid to contact the expanding tubes which
draws fluid into the tubes. The seals can be of differing
thicknesses, compositions, etc. so the seals dissolve at different
rates. Thus, first one seal dissolves and the associated tube
expands and fills with liquid. A second seal dissolves and that
tube fills and so on until the liquid is absorbed. When all the
liquid is absorbed, untriggered tubes remain for the next insult.
The arrangement of the tubes allows time delayed mass liquid
transport as each tube becomes contacted with liquid. By
controlling the amount and/or nature of the material sealing the
tubes, provision may be made to accommodate a number of liquid
insults over an extended time period. Such a structure finds
particular application as, for example, an overnight bedpad.
FIG. 3 is a view of an embodiment like that of FIG. 2 except that
in this case tubes 40 each have multiple liquid soluble seals 46
along its length which can extend outside of the target zone 42
into the peripheral zone 44. This arrangement accommodates multiple
insults over a larger area of the product. It also provides
additional paths the fluid can take in case the primary path is
blocked by the swelling of a superabsorbent, e.g., gel blocking. By
varying the amount of expandable material in the tubes the drawing
forces on the liquid can be controlled to insure that the full
capacity of each tube is available.
FIGS. 4 and 5 illustrate in greater detail the operation of a tube
50 as described with respect to FIGS. 2 and 3. In this case tube 50
is initially compressed as in FIG. 4 and contains wicking fibers 52
and superabsorbent particles 54. A single liquid soluble seal 56 is
located in target area 58. As shown in FIG. 5, after liquid
contact, the seal 56 has dissolved, the compressed tube has
expanded, and the superabsorbent particles 54 have swollen to
further expand the tube 50. This expansion created suction that
acted to draw the liquid through the tube to the peripheral area
60. It may also be desirable to have parallel and/or perpendicular
channels in liquid communication with the superabsorbent filled
tubes to provide additional liquid paths which will not gel
block.
FIGS. 6 and 7 are views like that of FIGS. 4 and 5 except that the
wicking fibers and superabsorbent particles are replaced by
compressed, expandable foam material 62. With a liquid insult and
dissolving of seal 56, the material has expanded in FIG. 7 causing
the tube 50 to expand and draw liquid through the tube from the
target area 58 to the peripheral area 60. The foam could be made up
of or contain a superabsorbent material.
FIGS. 8 and 9 illustrate yet another embodiment. In this case, a
collection pouch 70 is attached in the target area 74 by liquid
soluble attachment seal 76 and connected by retraction band means
78 to position 80 in peripheral area 82. A liquid insult releases
pouch 70 containing the liquid to be drawn by retraction means 78
to the peripheral area 82. As will be apparent to those of skill in
the art, this arrangement may be facilitated by locating the pouch
70 between layers in the product so that movement can be readily
achieved. Also, the point of attachment by the liquid soluble
adhesive is desirably away from the first liquid contact point so
as to allow the pouch to collect liquid prior to release.
FIGS. 10 and 11 illustrate a further embodiment where compressed
material including superabsorbent fibers 94 of the type described
is formed into channels 90 that have a plurality of liquid soluble
seals 92. When contacted with a liquid, the channels 90 expand in a
controlled manner to deliver liquid along the channels to the
peripheral zones (not shown).
Other embodiments of the invention will be apparent that provide
for mass liquid movement by liquid activated mechanical means
causing liquid to be drawn from a target zone to a peripheral zone.
Also as has been shown, the different embodiments may be used in
single or multiple form and, of course, can be combined for even
greater effect. The particular application as well as cost and ease
of manufacture considerations will help determine the best
construction in each case.
As will also be appreciated by those skilled in the art, selection
of materials for the structures of the invention must be made from
those that will achieve the desired results. Examples for specific
applications will be given although others will suggest themselves
to those of ordinary skill and are intended to be embraced by the
description herein and the appended claims.
The liquid soluble seals and attachment means used will depend on
the nature of the liquid for which the product is intended. For
disposable diaper applications to contain aqueous liquids like
urine and runny bowel movement ("BM"), for example, water soluble
adhesive compounds based on polyvinyl alcohol can be used. Specific
examples include the ELVANOL.RTM. brand series of fully hydrolyzed,
partially hydrolyzed and copolymers of PVOH available from DuPont
as well as TEXTAC.RTM. series of water soluble adhesives available
from Texas Screen Process Supply Company, Dallas, Tex. It is, of
course, not necessary that the seal partially or totally dissolve
so long as it releases. Compounds that lose adhesive properties on
liquid contact may also be used.
The material used for containment of the liquid in tubes, bags and
the like as described for mass transport must, of course not be
liquid soluble, at least under conditions of use. The containment
structures must also be sufficiently "robust" or have physical
properties that maintain the ability to provide mass transport
under use conditions. For disposable diaper applications, these
containment tubes, bags and the like may be made from inexpensive
polymeric materials such as polyolefins, polyesters and the like.
For those embodiments requiring stretch of the containment devices,
thermoplastic elastomers such as Kraton.RTM. brand from Shell
Chemical Company of Houston Texas can be used. KRATON.RTM. block
copolymers are available in several different formulations, a
number of which are identified in U.S. Pat. Nos. 4,663,220 and
5,304,599, hereby incorporated by reference in their entireties.
Polymers composed of an A-B-A-B tetrablock copolymer may also be
used in the practice of this invention. Such polymers are discussed
in U.S. Pat. No. 5,332,613 to Taylor et al. In such polymers, A is
a thermoplastic polymer block and B is an isoprene monomer unit
hydrogenated to substantially a poly(ethylene-propylene) monomer
unit. An example of such a tetrablock copolymer is a
styrene-poly(ethylene-propylene)-styrene-poly(ethylene-propylene)
or SEPSEP block copolymer available from the Shell Chemical Company
of Houston, Tex. under the trade designation KRATON.RTM..
A particular well suited tube is made from a TYGON.RTM. tube having
an outside diameter of about 1.9 centimeters, an inside diameter of
about 1.3 centimeters, and a length of about 17.8 centimeters.
Other suitable materials from which the liquid transfer tubes may
be are manufactured are commercially available from Baxter
Diagnostics, a business having offices located in McGraw, Ill.
under the trade designation S-50-HL. Another suitable tube is
available from Advanced Technology Products Co., a business having
offices located in Milford Center, Ohio, under the trade
designation 532-30-WH and having an inside diameter of from about
0.2 to about 0.7 centimeters.
For suction devices like bulbs and the like that must expand to
pull liquid to the peripheral zone, somewhat stronger resilient
materials may be used. Examples include thicker versions of the
previously mentioned polymers for the tubes as well as other
resilient materials capable of maintaining a compressed form and
then reacting under changed conditions to expand.
For those embodiments using a compressed expandable foam material,
such foams are also known and include, for aqueous liquid
applications, regenerated cellulose and other
compressible/expandable foams. Suitable materials include
expandable foams, compressed cellulose sponges, or the like.
Particularly desirable expandable foams include those having open,
large cell, reticulated structures. Examples of such expandable
foams are available from O-Cell-O, General Mills, Inc., Tonawanda,
N.Y., USA, and Industrial Commercial Supply Co., Akron, Ohio, USA.
The material may be softened by mechanical means or other suitable
techniques so as to be less noticeable until urination occurs. One
such means that is effective with compressed cellulose sponge is to
run the material through a set of meshed gears with the gap between
the gears set so that the material is sufficiently scored to make
it pliable.
For those embodiments requiring a swelling material to expand a
container to create the suction necessary for mass liquid
transport, superabsorbents having this property with respect to
aqueous liquids are well-known. These are available in a number of
forms including fibers, films, foams, particles, and the like as
described previously in detail.
For those embodiments using a retractive force to move a liquid
collection device, suitable elastic material in a stretched
condition may be employed. Such materials include, without
limitation, thermoplastic and rubber elastomers, some of which have
been previously described. It is also contemplated to use liquid
shrinkable materials such as a stretched elastic film or foam
coated with a water soluble polymer. The water soluble polymer
dissolves on contact with liquid and the elastomer is allowed to
retract. Also as previously described, extended superabsorbent
fibers or filaments in an extended condition that contract on
liquid contact may be used.
The other components of the devices in accordance with the
invention are not critical and may be selected from those
conventionally used for the particular product as well as such
components as may be developed for the purpose. Liquid pervious
liners, for example, often comprise nonwovens such as spunbonded
polyolefin webs or perforated films. Absorbents used often contain
woodpulp fibers and may contain additives such as superabsorbent in
powder or fiber form for increased absorbency. The liquid
impervious backing may be made from various films of polyolefins
and may contain fillers and/or be combined with a nonwoven layer
for cloth-like, breathability, or other desired properties. Again
depending on the particular use, elements such as fasteners, waist
and leg dams, elastic waist or leg cuffs may be added. For
additional details of these and other components that are useful,
reference is to U.S. Pat. No. 4,704,116 to Enloe dated Nov. 3, 1987
and U.S. Pat. No. 5,865,825 to Schlinz dated Feb. 2, 1999, the full
contents of each of which is incorporated herein by reference.
Example 1
This example demonstrates the ability of vacuum assisted resilient
sponge material to draw aqueous liquids by mass transport. A large
zip lock plastic bag and an open cell 6 inch by 6 inch auto sponge
obtained from Home Depot, Inc. were used. The sponge was placed
within the bag and located so as to provide about 5 to 6 inches of
space at each end within the bag. The bag and contents were
compressed in a hydraulic press until virtually all air was removed
and the bag sealed. The sponge partially expanded when the bag was
removed from the press creating a partial vacuum inside the bag. A
hook was attached to the bottom weighing unit of an electronic
balance. The sealed bag was attached to the balance hook with the
sealed end immersed in about one to two inches of water. Holes were
cut in the sealed end of the bag, and the weight change of the bag
over a ten minute period recorded as in FIG. 12 which compares the
same sponge material without the vacuum assist.
Example 2
This example demonstrates the use of a tube as a mass transport
means in accordance with the invention. A one foot length of
plastic tubing (Tygon.RTM. B-44-3, 3/8 inch diameter from Norton)
was sealed at one end using marine adhesive (Goop.RTM. brand).
Using a hydraulic press the tube was pressed to essentially force
all of the air was evacuated from the tube, and the opposite end
sealed using a channel lock vise grip leaving a three inch portion
of unevacuated tubing past the seal. Liquid gelatin (Knox.RTM.
brand or equivalent) was placed into the unevacuated portion, and
the tubing was placed in a standard refrigerator to allow the
gelatin to solidify. The test used in Example 1 was repeated after
the gelatin had solidified except that weight determinations were
not made. It was observed that the gelatin acted to regulate the
mass liquid transport, and it was noted that there was no
discernible change over the first thirty seconds. Then the tube
took on water in a matter of a few seconds and, after about thirty
seconds, had reassumed its circular cross-section. No change took
place over an additional three minutes, but, upon removal,
thereafter, the gelatin retained the water within the tube. Thus
the gelatin with the vacuum assist extracted the water into the
tube then acted as a plug to retain it.
The above description of the best mode and other examples is not
exhaustive of embodiments of the invention, and others will be
apparent to those of ordinary skill. The appended claims are
intended to describe all such embodiments as well as equivalents as
may be embraced by the claims.
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